Field of Invention
The present invention relates to antenna technology field, and more particularly to 5G (5th generation mobile networks) MIMO (Multiple-Input-Multiple-Output) antenna field and Metamaterial field.
Description of Related Arts
In recent years, with the continuous development of mobile communication and the pressing demand for high data rate, stable communication quality and various complicated applications, 5G has become one of the hottest research topics in the mobile communication industry in the world, such as Cisco and Intel of USA, Metis, 5GPP and NGMN of EU, ARM AdHoc of Japan, 5G Forum of Korea and IMT-2020 of China. Under the premise of reasonable instrument cost the booming demand for wireless communication brings a series of requirements for 5G, which are serving more clients, higher data rate, supporting unlimited connection and providing personalized experience. These requirements demand wider bandwidth, while the low frequency band (800 MHz-3 GHz) is occupied by various current communication formats. The current low frequency band spectrum resource is unable to fulfill the 5G requirement. The current research on 5G focuses on the spectrum resource over 3 GHz. In 2014, USA published the research on applying frequency band over 24 GHz to advanced mobile service, in which the suitable candidate frequency bands for 5G are publicly discussed and 12 frequency bands are chosen. In 2012, EU started the research on frequency allocation within the range of 6 GHz-100 GHz, spectrum allocation and spectrum usage and published reports on 5G spectrum requirement and principle for spectrum usage in 2013 and 2014, respectively. In 2015, UK published draft version to solicit opinions on the high-frequency resource for 5G within the industry and identified 6 potential 5G frequency band. In 2016, the Japanese operator NTT Docomo worked with Samsung Group to finish the related research on 5G under 28 GHz frequency band on high-speed railway, wherein the 28 GHz frequency band is one of the designated candidate frequency bands of the 5G network of the Ministry of Internal Affairs and Communications of Japan. In recent years, Korea submitted almost 10 candidate frequency bands for 5G over 6 GHz to international organizations. Under IMT-2020 frame, China carried out a series of research on 5G spectrum demand prediction, candidate frequency band selection, broadcasting property measuring of certain frequency bands and electromagnetic compatibility. Lead by China State Radio Monitoring Center and State Radio Spectrum Management Center an estimate for overall 5G spectrum demand toward 2030 is achieved and research on priority of 6 GHz-100 GHz candidate frequency band and so on are carried out. Recently, China further narrowed the 5G candidate high frequency range of 6 GHz-100 GHz with the consideration of the new research trends domestic and abroad. Besides, the Chinese 5G research teams such as China mobile and Huawei carried out research on the 5G instruments for frequency range around 3.5 GHz and successfully released related experimental prototype in 2016.
3 GHz-30 GHz frequency range is the key research direction and development trend for the future 5G. As an important part of the wireless communication, the research on 5G antenna will be challenged with various problems. 5G antenna is required to adopt various communication modes at the same time to meet the people's daily demands. Besides, the trend of reducing the size of mobile communication devices limits the size of the antenna extremely. How to realize ultrawide frequency bands of 3 GHz-30 GHz within limited space is a challenge for all the researchers. MIMO technology is becoming an indispensable part of the 5G antenna due to the high data rate and high communication quality required by the modern mobile communication. The antenna unit increase and separation required in MIMO technology bring further challenges for related research.
At present, the metamaterial as a kind of new artificial material has some exotic electromagnetic features such as negative permittivity, negative permeability and negative refractive index, which doesn't appear in the naturally occurring material. The metamaterial attracts wide attention and is well studied. When designing the MIMO antenna, the unit separation of antenna is effectively improved by adopting the metamaterial unit without damage on antenna performance, which reduces the size of the MIMO antenna and realizes the wideband. Obviously, the metamaterial is the hot research topic in the related fields.